Dictionary

donkey's years en · NOUN

Pronunciation

• (Australia) audio

Etymology

1876 or earlier. Possibly chosen because donkeys can be long-lived animals. Likely directly related to donkey's ears, a less frequently used rhyming slang term for years.https://wordhistories.net/2016/06/30/donkeys-years/

Meanings

1. (Commonwealth, Ireland, UK, idiomatic, plural, plural-only) A long time, years and years.
   • Didn't you ask him how long it had been in his possession? I can't recollect that. I might have done so. Didn't he say for years and years and donkey's years? 1876, The Salisbury Times
   • With a heavy make-up, you’ll be the cutest vamp I’ve seen in donkey's years. 1923, The Bridgeport Telegram:

Forms

wikipedia: rhyming slang